Engine Test Apparatus Using Laser Doppler Velocimetry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional engine test apparatuses face limitations in measuring engine characteristics with high accuracy due to restricted frequency range for inertia compensation and resonance issues when using dynamometer rotation speed for control, which affects the accuracy of engine behavior measurement, especially during startup and variations caused by explosion.
Innovation Solution
Incorporating a Doppler velocimeter to contactlessly measure the rotation speed of the engine's output shaft, which is then used to control the dynamometer, allowing for accurate measurement and compensation without frequency limitations, and optionally using pairs or additional sensors to cancel noise from engine body vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the rotation speed of the dynamometer is used for inertia compensation control, then the control system can be simplified, but the frequency range for inertia compensation is limited and resonance occurs
Solution Approach 1:
The patent introduces a rotation speed sensor as an intermediary device that directly measures the engine output shaft's rotation speed, rather than using the dynamometer's rotation speed as a proxy. This intermediary measurement enables accurate inertia compensation across the full frequency range by providing direct feedback about the engine's actual rotational state, eliminating the resonance issues and frequency limitations associated with using dynamometer speed as a substitute measurement.
2Measurement precision
If contactless measurement is implemented using Doppler velocimeter, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent replaces traditional mechanical contact-based rotation speed sensors with a Doppler velocimeter that uses optical fields to measure rotation speed contactlessly. This substitution eliminates mechanical wear and interference, providing high-accuracy measurement of the engine output shaft's rotation speed without physical contact, thereby improving measurement precision while avoiding the limitations of mechanical sensor systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-accuracy measurement of engine characteristics by providing an accurate rotation speed for dynamometer control, effectively overcoming the limitations of conventional systems and allowing for precise reproduction of engine behavior during startup and variations.
Implementation Method 1
a Doppler velocimeter configured to emit laser light to the one end of the shaft or the output shaft of the engine to contactlessly measure a rotation speed of the output shaft of the engine
Data Source
AI summary
An engine test apparatus includes a dynamometer connected to an engine through a shaft, and a control calculation device configured to control operations of the engine and the dynamometer. The shaft has one end connected to an output shaft of the engine, and the other end connected to a rotation shaft of the dynamometer, and includes a Doppler velocimeter configured to emit laser light to the one end of the shaft or the output shaft of the engine to contactlessly measure a rotation speed of the output shaft of the engine, and transmit the measured rotation speed to the control calculation device. The control calculation device uses the rotation speed transmitted from the Doppler velocimeter to control the operation of the dynamometer.